Dry matter intake and weight gain of grazing heifers on tall fescue and perennial ryegrass

Climate change results worldwide in more extreme weather conditions like longer dry periods during the growth season. The increased frequency of these periods jeopardizes the production of high quality forage grass. Tall fescue (Festuca arundinacea Schreb.) is less sensitive to summer drought than perennial ryegrass (Lolium perenne L.), however, grazed tall fescue is supposed to lead to less voluntary intake and a lower digestibility, inhibiting the adoption of this species in North-West European dairy production. There is however a paucity of results, particularly with new varieties of tall fescue bred for an improved digestibility. We hypothesized that the life weight gain of grazing dairy heifers is comparable when grazing on recently bred varieties of tall fescue and perennial ryegrass. To investigate this, pastures with either perennial ryegrass or tall fescue were grazed by two groups of heifers in a cross-over design. Surprisingly, heifers grazing on tall fescue showed a significantly greater life weight gain, whereas dry matter intake was not different. Although more research over different years and conditions is needed, this finding underpins the value of tall fescue for grazing.